A leather needle is overkill. I use a size 11 sharp needle for 90% of my sewing, including sewing velcro. I use a straight stitch machine with a narrow foot or a zipper foot on a zig zag machine so I'm sewing at the flat edge of the velcro. The last time I sewed velcro I was making some travel sewing tool organizers on a Singer 301. Even using a stiff interfacing I didn't have to change my needle or cotton thread.
Cari